Evidence of metabolic resistance to insecticides in sandfly population from Kala-azar endemic areas of Malda, West Bengal, India

This study was undertaken to estimate the levels of metabolic enzyme among vector sandfly from VL endemic areas of Malda, West Bengal. A total of 92 unfed adult females sandflies of each study sites were used for estimation of activity/levels of acetylcholinesterase, esterases, glutathione-S-transferase and cytochrome P450 mono-oxygenase by microplate assay method. More than 97% of sandfly population showed sensitive acetylcholinesterase activity, which is indicative of malathion sensitivity. Increased alpha and beta esterase activity was recorded among one-third of sandfly population. More than 50% of the study population showed elevated glutathione-S-transferase level and mean activity of cytochrome P450 mono-oxygenase was slightly above the cut off level. Higher level of estarases and cytochrome P450 mono-oxygenase among significant proportion of sandfly population might be an early warning signal of pyrethroid resistance. It should be monitored closely in various VL endemic areas of West Bengal.